Sorting nexin-4

Sorting nexin-4 (SNX4) is a 451-amino acid cytoplasmic protein that regulates endocytosis and intracellular trafficking pathways (UniProt: O95219). It functions in recycling the transferrin receptor to prevent its degradation and participates in autophagosome assembly by regulating ATG9A trafficking and recycling. These roles position SNX4 at the intersection of membrane dynamics and autophagy regulation.

SNX4 is expressed broadly in human tissues and participates in fundamental cellular homeostasis processes involving endosomal and autophagosomal biology (UniProt: O95219). No disease associations are listed in the UniProt record.

SNX4 shows reduced expression in Alzheimer's disease brain tissue. According to Chaparral AD proteomics data from post-mortem AD brain compared to age-matched controls (TMT-labeled, 4 subcellular fractions), SNX4 is downregulated with a mean log2 fold-change of −0.33 (Chaparral AD proteomics). This downregulation may reflect impaired endocytic recycling or autophagosomal dysfunction, processes thought relevant to AD pathogenesis.